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<p>This paper investigates the effects of different pulsation frequencies and amplitudes on cooling performance in a 90° ribbed channel with <i>AR</i>=3. Simulations are conducted using the SS<i>T k-ω</i> turbulence model in OpenFOAM. Strouhal numbers <i>St</i><sub><i>F</i></sub> from 0.02 to 0.14 and amplitudes <i>A</i> up to 0.5 are considered. The cooling performance is more sensitive to pulsation frequency than to amplitude. The channel-averaged Nusselt number increases with frequency, reaching a maximum enhancement of 73.3 % at <i>St</i><sub><i>F</i></sub> = 0.06. At low frequencies of <i>St</i><sub><i>F</i></sub> = 0.02, the pulsating flow promotes the periodic formation of large-scale unsteady separation vortices, which disturb the thermal boundary layer. In the mid-frequency range of <i>St</i><sub><i>F</i></sub> = 0.06–0.14, the shortened pulsation period accelerates vortex generation, further enhancing boundary layer disruption. Pulsation amplitude exhibits a linear enhancement effect on heat transfer at low frequencies, but offers limited benefits in the mid-frequency range, depending on flow regime transitions. These results indicate that the nonlinear interaction between vortex dynamics and thermal boundary layers, modulated by pulsation frequency.</p>

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Spatiotemporal effects of pulsating flow on heat transfer and pressure loss in a ribbed channel

  • 期刊论文

  • 发表日期：

    2026年5月11日

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  • Liang Zhou,
  • Bohan Zhang,
  • Tieyu Gao,
  • Peng Yang,
  • Zhihui Zhang,
  • Jianying Gong

摘要

This paper investigates the effects of different pulsation frequencies and amplitudes on cooling performance in a 90° ribbed channel with AR=3. Simulations are conducted using the SST k-ω turbulence model in OpenFOAM. Strouhal numbers StF from 0.02 to 0.14 and amplitudes A up to 0.5 are considered. The cooling performance is more sensitive to pulsation frequency than to amplitude. The channel-averaged Nusselt number increases with frequency, reaching a maximum enhancement of 73.3 % at StF = 0.06. At low frequencies of StF = 0.02, the pulsating flow promotes the periodic formation of large-scale unsteady separation vortices, which disturb the thermal boundary layer. In the mid-frequency range of StF = 0.06–0.14, the shortened pulsation period accelerates vortex generation, further enhancing boundary layer disruption. Pulsation amplitude exhibits a linear enhancement effect on heat transfer at low frequencies, but offers limited benefits in the mid-frequency range, depending on flow regime transitions. These results indicate that the nonlinear interaction between vortex dynamics and thermal boundary layers, modulated by pulsation frequency.